A man was arrested Thursday after he discharged a handgun aboard a King County Metro bus, according to Seattle police.

A man was arrested after he discharged a handgun aboard a King County Metro bus Thursday, according to Seattle police.

Seattle police spokesman Jeff Kappel said the shooting occurred shortly after 1 p.m. on the Route 125 bus, which serves Shorewood, White Center and South Seattle Community College.

It was not immediately clear whether the handgun was intentionally fired or accidentally discharged, Kappel said.

A woman on the bus said she had been grazed in the leg by the ricocheting bullet, but Seattle Fire Department medics found no visible signs of injury, according to a spokeswoman.

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Passenger Vaun Raymond said the suspect made a commotion when he got on the bus, making a lot of noise and causing a delay as he tried in vain to coax more of his friends into getting on and riding with him.

“With some people, you just know it’s trouble,” Raymond said.

He eventually sat down with a female companion, police said.

As the southbound bus approached Seneca Street on Third Avenue, passengers heard an “incredibly loud bang,” Raymond said. They didn’t realize it was a gunshot at first.

King County sheriff’s deputies, who were working as Metro Transit police, were standing at the street corner and also heard the noise, but they recognized it as a gunshot, Kappel said.

The deputies followed the suspect and his friend when the two got off the bus and headed into the Downtown Seattle Transit Tunnel at the University Street Station just a few feet away from the bus stop, police said. They were apprehended on the mezzanine level of the transit station. A handgun was recovered from the man, Kappel said.

Raymond said the experience wasn’t too upsetting, but he had been “inches away from disaster.”

Christine Clarridge: 206-464-8983 or cclarridge@seattletimes.com